S-65C is a premium material that exhibits at least 3% elongation in any direction at room temperature through controlled impurity ratios. It is used in the window frames, umbilical doors, and navigational base of the Space Shuttle. It has a lower oxide content but lower in strength than the standard grade, S-200F. It is the reference grade of beryllium for the International Thermonuclear Experimental Reactor (ITER) fusion energy program.

Please note that there are health hazards associated with beryllium, especially when present as airborne particles generated during processing. As with any material, be aware of hazards and take steps to reduce exposure to a safe level.

General beryllium information: Beryllium is one of the lightest metals and has a high strength-to-weight ratio, stiffness-to-weight ratio, and very high specific heat, thermal conductivity, and heat of fusion. It has significant ductility, is readily machined and can be rolled, drawn, or extruded. It finds applications in nuclear reactors (neutron moderator and reflector), X-ray sources/detectors (X-ray transparency), IR target acquisition systems, inertial guidance instruments, computer parts, other aircraft and satellite structures, and heat sink constraining cores. Beryllium is usually produced via a powder metallurgy process to improve machinability and mechanical properties.

Information provided by Materion Corporation (formerly Brush Wellman) and the references.